Conventional wisdom would have us believe the journey to a long and healthy life begins with 10,000 steps. Each and every day.
For those living a more sedentary lifestyle, it's a goal that can take some effort to maintain. We've also known for some time it's also almost certainly wrong.
By analyzing data on tens of thousands of people across four continents compiled between 15 existing studies, a team of researchers has landed on a more comfortable figure: the optimal number is probably closer to 6,000 steps per day, depending on your age.
Anything more is unlikely to further reduce your chances of stumbling into an early grave.
"So, what we saw was this incremental reduction in risk as steps increase, until it levels off," said University of Massachusetts Amherst epidemiologist Amanda Paluch when the study was released in March 2022.
"And the leveling occurred at different step values for older versus younger adults."
Humans are essentially built to ambulate. Evolution has honed our physiology to walk long distances, shedding heat easily as we tick-tock back and forth like inverted pendulums across the landscape in search of food and water.
This means our metabolisms, cardiovascular fitness, impact on our bones and muscles, and even our mental health are all tuned to appreciate a good hike. Squeezing just about any kind of stroll into our busy schedule will serve us well by helping us live longer, healthier, happier lives.
This is easier said than done for those pressed for time or lacking motivation, which is why tech companies invented small devices that help us keep track of the number of steps we take each day.
Half a century ago, the Yamasa Clock and Instrument Company in Japan sought to cash in on the buzz left by the 1964 Tokyo Olympics by producing a pedometer they called 'Manpo-kei' – a word that translates into 10,000 steps.
Why 10,000? Good old fashioned marketing. It's a nice, round number that sounds taxing enough to be a goal, but achievable enough to be worth striving for. What it doesn't have going for it is any scientific backing.
Having a single figure to promote to a general population is certainly useful. "It's such a clear communication tool for public health messaging," said Paluch.
But getting that number right could make the difference between encouraging everybody to get enough exercise and putting people off trying altogether.
In 2021, Paluch and her team published research based on a cohort of more than 2,000 middle-aged individuals living across the US. They found taking at least 7,000 steps a day reduced chances of premature death by 50 to 70 percent.
Those words 'at least' are doing some heavy lifting. With questions remaining over whether more is better, and whether squeezing all those steps into a more rapid pace is in any way useful, the research team widened their net to include previously published research.
Their 2022 meta-analysis included information collected on the health and step-counts of 47,471 adults from Asia, Australia, Europe, and North America. They found the 25 percent of adults who stepped the most each day had 40 to 53 percent lower chance of dying, compared with those in the bottom 25 percent of step-counts.
For adults aged 60 and older, this reduced risk topped out at around 6,000 to 8,000 steps a day. Pushing further might have other benefits, but a reduced chance of death isn't one.
The study found that those who are younger could do well to walk a little more, but there wasn't evidence that they'd necessarily live longer by walking more than 8,000 to 10,000 steps a day.
As for the rate of steps, the team found volume is what really matters.
"The major takeaway is there's a lot of evidence suggesting that moving even a little more is beneficial, particularly for those who are doing very little activity," said Paluch.
None of this is to say we wouldn't benefit from working our bodies harder in other ways.
Half an hour of intense activity each day could be a big boost for those of us who sit around a lot. Throwing in some strength training in old age could help our brains stay sharp and our hearts and bones stay health and strong.
But if nothing else, setting our sights on at least 6,000 to 8,000 paces before bedtime could be a far easier step towards a longer life.
This research was published in The Lancet: Public Health.
A version of this article was first published in March 2022.